This invention relates to an apparatus for false-twisting synthetic yarns, more particularly, a disc clutch false-twist texturing spindle whereby yarn, when drawn through the spindle, is rapidly twisted about the yarn's longitudinal axis by multiple rollers, called also "discs" thereby imparting a temporary high twist to the yarn, as a step in applying a permanent crimp to it.
False-twist texturing is a well known technique whereby a thermoplastic thread is overtwisted by various means and, through the action of heating and cooling, the deformation is stabilized before the thread is untwisted. Such twisting may be imparted by means of two or more overlapping multi-rim rollers having their axes parallel to one another, the overlapping portions of the multi-rim rollers imparting the temporary twist to the thread which passes across and against the peripheral edges of the rollers, the arrangement being such that the thread is deflected slightly from its normal direction of travel, as disclosed in Hilden U.S. Pat. No. 1,030,179. The yarn is unwound from a bobbin or spool by drawing it across the rollers (or into contact with other rotating surfaces) rotating substantially parallel to the direction of travel of the yarn across the rollers. Other systems have used parallel-running belts (in opposite directions) to impart such twisting to threads of yarn passing between the belts, as in Findlow U.S. Pat. No. 3,021,663. Regardless of the twisting medium used, the rotating surfaces have a coefficient of friction such as to twist the yarn without applying so much drag as to affect the orientation of the fibers making up the yarn.
By the Hilden process, the thread passes across the edges of only two overlapping rollers spinning the same direction. More recent devices have used three or more rollers, preferably three rollers located equidistant from one another (as on the vertices of an equilateral triangle, if the rollers were considered to be in one plane), such that the rollers' peripheral edges, when viewed along the axis central to the rollers and parallel to the axes about which the rollers rotate, form the vertices of an equilateral triangle, the rollers either having some distance between their peripheral edges in this central area, or overlapping somewhat. See, for example, Tully U.S. Pat. No. 2,923,121, disclosing a three-roller apparatus wherein the location of one of the rollers is adjustable to account for varying coefficients of friction of the rollers, and varying diameters of thread.
Because of the problems involved in adjusting the space between the rollers by movement of only one set of rollers, more recent systems, including that on which the subject invention is used, allow for adjustment of the distances between the rollers by movement of all three sets of rollers, rather than just one, as in Tully. See, for example, Schuster et al British Pat. No. 1,376,272, disclosing a system for making all the roller sets simultaneously and symmetrically adjustable, so that the rollers always lie at the vertices of an imaginary equilateral triangle, through the center of which runs the thread of yarn. Such a system eliminates the disadvantage in Tully of creating an isosceles triangle roller configuration (rather than the desired equilateral configuration) by movement of only one roller for adjustment purposes.
All of the above systems involving overlapping rollers have, however, the further disadvantage of difficulty of threading the yarn through the rollers. To do that, one or more of the sets of rollers are commonly moved aside, as by a hinge apparatus in Tully, allowing one set of rollers to pivot away from the others about a hinge axis parallel to the roller axes, so that the yarn may be threaded by hand between the two remaining rollers. The thread is generally passed through an orifice from a guide tube through which the thread runs, from there, between the displaced rollers, and finally through an exit guide on the other side of the rollers. The hand-threading method is incompatible with an integrated spin-texturing process in which, after a thread is spun by continuous extrusion, the thread is textured after or simultaneously with the thread-twisting in a continuous, integrated operation. The removed roller is then replaced in position so that the spindle may be operated. The Schuster system is operated by disengaging all threee roller sets, moving them aside, then moving them back in place for yarn twisting after the yarn has been threaded by hand through the area between the rollers.
The primary disadvantage of these systems is the time and difficulty involved in hand threading the rollers. A solution to this problem, provided by the subject invention, is a system eliminating the need to thread by hand the yarn through the displaced rollers.